This application claims the priority benefit of Japanese Patent Application No. 2000-49717, filed Feb. 25, 2000, the entire disclosure of which is incorporated herein by reference.
1. Field of the Invention
The invention relates to a semiconductor chip having a plurality of electrodes on its main surface and, more specifically, to such a semiconductor chip being suitable for a BGA (Ball Grid Array) type semiconductor device. The invention also relates to a BGA type semiconductor device having the semiconductor chip.
2. Description of the Related Art
Great technological advances have occurred in electrical equipment such as cellular phones using electrical circuits or electrical devices. A semiconductor device is used in most of these electrical circuits or electrical devices.
Because of a great progress of the electrical equipment regarding its function, the semiconductor device should have multi-function features, so that the number of terminals, which are formed on the semiconductor device, are increased wherein the terminals receive input signals from an external device or output signals to the external device.
Generally, it has been required that the size or the weight of the electrical equipment be reduced. For example, the size and the weight of cellular phones are reduced year after year. Therefore, to meet this requirement, it is also required that the size of the semiconductor device within the electrical equipment be reduced. To satisfy this requirement for the semiconductor device, a BGA-type semiconductor device has been developed.
The BGA-type semiconductor device includes a substrate having opposite first and second surfaces. A plurality of terminals are formed on both surfaces. On the first surface, a plurality of ball electrodes, which are formed of a metallic material such as solder are formed on the terminals. Each ball electrode is connected electrically to one of the terminals formed on the second surface by an internal wire formed in the substrate.
A semiconductor chip includes opposite front-main and back surfaces. The semiconductor chip is mounted at a predetermined location on the second surface of the substrate wherein the back surface is facing to the second surface of the substrate. On the main surface of the semiconductor chip, a plurality of electrodes, which are for connecting to the power supply or ground and for inputting or outputting signals, are formed. Each electrode on the main surface of the semiconductor chip is connected to one of the terminals on the second surface of the substrate by a bonding wire. The semiconductor chip and the bonding wires are sealed by insulating material.
Compared to other semiconductor device""s structures, such as the DIP (Dual In-line Package) or the QFP (Quad flat package), the BGA type semiconductor device can have more electrodes without enlarging its size because the electrodes can be disposed in a two-dimensional array. Further, to cope with problems resulting from the increased number of the electrodes on the main surface of the semiconductor chip, the electrode is disposed in two lines with a zigzag configuration. The BGA type semiconductor device is mounted on a motherboard so that the ball electrodes are electrically connected to a print circuit formed on the motherboard.
Generally, while there are many electrodes on the chip, which are used for the power supply electrodes and for the ground electrodes, one of the terminals on the substrate is used for the power supply terminal, and one of the terminals on the substrate is used for the ground terminal in the BGA type semiconductor device because the number of terminals being formed on the substrate is restricted. Therefore, the ground terminal is open-rectangular-frame-shaped, and it encompasses a chip-mount area of the substrate. Further, the power supply terminal is also open-rectangular-frame-shaped, and it encompasses the flame-shaped ground terminal. A plurality of I/O signal terminals are disposed in a line, or in two lines with a zigzag configuration, along the outside of the frame-shaped power supply terminal.
However, in this configuration of the electrodes and terminals, there is a problem to be solved in order to avoid their contacts with bonding wires. That is, since the frame-shaped ground terminal on the substrate is disposed at a location closer to the semiconductor chip than the locations of other terminals, the electrodes on the semiconductor chip for the ground connection should be disposed at the outside line of the two lines closer to the side of the semiconductor chip than the inside line. Therefore, the outside line of the electrodes on the semiconductor chip of the two lines with the zigzag configuration includes the power supply electrodes, the ground electrode and the I/O signal electrodes. As a result, the number of the electrodes in the outside line is more than that in the inside line, which is close to the center of the semiconductor chip than the outside line.
According to this configuration, an arrangement of the electrodes on the semiconductor chip is very restricted. This causes an arrangement of the terminals on the substrate to be very restricted also. When the arrangements of both electrodes and terminals are restricted, the number of the ball electrodes is also restricted. If the number of the ball electrodes will not be restricted, a pitch between electrodes or a pitch between terminals becomes very tight as the number becomes large. As a result, it is difficult to avoid their contacts with bonding wires.
An objective of the invention is to provide a semiconductor chip that improves the design flexibility as to an arrangement of electrodes.
Another objective of the invention is to provide a semiconductor device having the semiconductor chip, which improves the design flexibility as to an arrangement of the electrodes.
Yet another objective of the invention is to provide a semiconductor chip capable of having an increased number of terminals.
A further objective of the invention is to provide a semiconductor device having the semiconductor chip capable of having an increased number of terminals.
According to one aspect of the invention, to achieve one or more of the objectives described above, a semiconductor chip includes a main surface having a plurality of sides, a plurality of signal electrodes formed on the main surface along the sides, the signal electrodes along one of the sides being disposed in a first area of a first length, and a power supply electrode formed on the main surface along the sides, the power supply electrode along the one of the sides being disposed in the second length, which is longer than the first length, between the one of sides and the signal electrodes.
According to another aspect of the invention, to achieve one or more of the objectives described above, a semiconductor device includes a substrate and a semiconductor chip. The substrate includes opposite first and second surfaces, the second surface including a chip-mounting area where the semiconductor chip is mounted, a plurality of signal terminals formed on the second surface at the outside of the chip-mounting area, a power supply terminal formed on the second surface between the chip-mounting area and the signal terminals, and a ground terminal formed on the second surface between the chip-mounting area and the signal terminals. The semiconductor chip includes a main surface having a plurality of sides, a plurality of signal electrodes formed on the main surface along the sides, the signal electrodes along one of the sides being disposed in a first area of a first length, and each signal electrode being connected to one of the signal terminals electrically, and a power supply electrode formed on the main surface along the sides, the power supply electrode along the one of the sides being disposed in a second area of the second length, which is longer than the first length, between the one of the sides and the signal electrodes, and the power supply electrode being connected to the power supply terminal.
The above and further objects and novel features of the invention will more fully appear from the following detailed description, appended claims and accompanying drawings.